1. Field of the Invention
The present invention generally relates to a motor and, more particularly, to a motor with an oil storage function.
2. Description of the Related Art
Conventional motors often include a base. A shaft tube is arranged at the center of the base for receiving a bearing to be coupled to a shaft of a rotor. A stator may be fitted around the shaft tube and drive the rotor to rotate.
The motors usually have an oil chamber in the shaft tube for storing lubricating oil. The lubricating oil makes the shaft rotate smoothly and prolongs the service life of the motor. Taiwan Patent Publication Nos. 200712335 entitled “A MOTOR WITH AN OIL LEAKAGE PREVENTION STRUCTURE”, 200612044 entitled “AN OIL LEAKAGE PREVENTION STRUCTURE FOR A SHAFT”, and 200717976 entitled “A BEARING WITH AN OIL BUFFERING AND STORING FUNCTION” disclose several motors with oil storage functions. In these applications, the motors form an expansion portion in the shaft tube or form a shrinkage portion on the top of the bearing. After a shaft tube assembly is installed in the shaft tube, an oil chamber will be formed based on the expansion portion or the shrinkage portion for accommodation of lubricating oil. The shaft tube assembly may be a positioning ring (lid) or the like. However, the oil chamber is not large enough to accommodate the required quantity of lubricant oil, as described in detail later.
As an example, FIG. 1 shows a conventional motor 9 disclosed in Taiwan Patent Publication No. 200712335. The motor 9 includes a stator 91, a rotor 92, a shaft tube 93, a bearing 94 and a positioning ring 95. The stator 91 is fitted around the shaft tube 93. The shaft tube 93 forms a hole 931 with a small diameter, as well as a hole 932 with a large diameter. The bearing 94 is installed in the shaft tube 93. The rotor 92 has a shaft 921 coupled with the bearing 94. The positioning ring 95 is installed in the hole 932. In this arrangement, the hole 932, the positioning ring 95 and the bearing 94 will jointly form an oil chamber 96.
In the motor 9, after the positioning ring 95 is installed in the shaft tube 93, the positioning ring 95, the hole 932 and the bearing 94 will jointly form the oil chamber 96. The positioning ring 95 also prevents the lubricant oil from leaking out of the shaft tube 93. However, the positioning ring 95 takes up a larger space in the shaft tube 93 when the positioning ring 95 is installed in the shaft tube 93. As such, the available space in the oil chamber 96 becomes smaller. Therefore, the oil chamber 96 will not be able to sufficiently accommodate the quantity of lubricant oil necessary for proper and efficient operation of the motor 9, resulting in a shortage of lubricant oil when the motor 9 operates for a long duration of time. This will hinder or even halt the operation of the motor 9, shortening the service life of the motor 9.
Furthermore, it not only causes inconvenient assembly but also increases the component quantity of the motor 9 when the positioning ring 95 is used, leading to high cost of the motor 9.
In light of the above problems, it is necessary to improve the conventional motor 9.